To predict the remaining useful life(RUL) for a class of nonlinear multi-degradation systems, a method is presented. In the real industrial processes, systems are usually composed by several parts or components, and t...To predict the remaining useful life(RUL) for a class of nonlinear multi-degradation systems, a method is presented. In the real industrial processes, systems are usually composed by several parts or components, and these parts or components are working in the same environment, thus the degradations of these parts or components will be influenced by common factors. To describe such a phenomenon in degradations, a multi-degradation model with public noise is proposed. To identify the degradation states and the unknown parameters, an iterative estimation method is proposed by using the Kalman filter and the expectation maximization(EM) algorithm. Next, with known thresholds,the RUL of each degradation can be predicted by using the first hitting time(FHT). In addition, the RUL of the whole system can be obtained by a Copula function. Finally, a practical case is used to demonstrate the method proposed.展开更多
Hydraulic servo system plays a significant role in industries, and usually acts as a core point in control and power transmission. Although linear theory-based control methods have been well established, advanced cont...Hydraulic servo system plays a significant role in industries, and usually acts as a core point in control and power transmission. Although linear theory-based control methods have been well established, advanced controller design methods for hydraulic servo system to achieve high performance is still an unending pursuit along with the development of modem industry. Essential nonlinearity is a unique feature and makes model-based nonlinear control more attractive, due to benefit from prior knowledge of the servo valve controlled hydraulic system. In this paper, a discussion for challenges in model-based nonlinear con- trol, latest developments hydraulic servo systems are and brief perspectives of presented： Modelling uncer- tainty in hydraulic system is a major challenge, which includes parametric uncertainty and time-varying distur- bance; some specific requirements also arise ad hoc difficulties such as nonlinear friction during low velocity tracking, severe disturbance, periodic disturbance, etc.; to handle various challenges, nonlinear solutions including parameter adaptation, nonlinear robust control, state and disturbance observation, backstepping design and so on, are proposed and integrated, theoretical analysis and lots of applications reveal their powerful capability to solve pertinent problems; and at the end, some perspectives and associated research topics （measurement noise, constraints, inner valve dynamics, input nonlinearity, etc.） in nonlinear hydraulic servo control are briefly explored and discussed.展开更多
The error vector magnitude（EVM） is extensively applied as a metric for digital transmitter signal quality compliance in modern communication systems.This article is focused on the effects of local oscillator（LO） p...The error vector magnitude（EVM） is extensively applied as a metric for digital transmitter signal quality compliance in modern communication systems.This article is focused on the effects of local oscillator（LO） phase noise and nonlinear distortion of power amplifier on EVM.This article contributes to below aspects.First,the relationships between EVM and two effects,LO phase noise and nonlinear distortion of power amplifier,are derived and expressed.Second,to simplify the expression,the third-order intermodulation distortion（IMD3） is used to calculate the EVM.Then,an expression for the EVM is derived based on the digital transmitter model that considers local oscillator phase noise and nonlinear distortion of power amplifier.Finally,the math formula of bit error rate（BER） versus EVM is given which can be easier and more useful to predict BER,according to analysis of the relationship between EVM and signal to noise rate（SNR）,inspired by the works of Rishad,Md.Shahriar and AHM,2006.Simulations are carried out to display the performance of EVM based on these relationships.展开更多
基金supported by the National Natural Science Foundation of China(6129032461473164+1 种基金61490701)the Research Fund for the Taishan Scholar Project of Shandong Province of China(LZB2015-162)
文摘To predict the remaining useful life(RUL) for a class of nonlinear multi-degradation systems, a method is presented. In the real industrial processes, systems are usually composed by several parts or components, and these parts or components are working in the same environment, thus the degradations of these parts or components will be influenced by common factors. To describe such a phenomenon in degradations, a multi-degradation model with public noise is proposed. To identify the degradation states and the unknown parameters, an iterative estimation method is proposed by using the Kalman filter and the expectation maximization(EM) algorithm. Next, with known thresholds,the RUL of each degradation can be predicted by using the first hitting time(FHT). In addition, the RUL of the whole system can be obtained by a Copula function. Finally, a practical case is used to demonstrate the method proposed.
基金Acknowledgements This work was supported in part by the National Natural Science Foundation of China （Grant No. 51675279）, the China Postdoctoral Science Foundation funded project （Grant Nos. 2014M551593 and 2015T80553）, and the Natural Science Foundation of Jiangsu Province in China （Grant No. BK20141402）. The author also wants to express his appreciation to Prof. B. Yao for hosting his visit at Purdue University from October 2010 to October 2011, and the guidance in adaptive and robust design.
文摘Hydraulic servo system plays a significant role in industries, and usually acts as a core point in control and power transmission. Although linear theory-based control methods have been well established, advanced controller design methods for hydraulic servo system to achieve high performance is still an unending pursuit along with the development of modem industry. Essential nonlinearity is a unique feature and makes model-based nonlinear control more attractive, due to benefit from prior knowledge of the servo valve controlled hydraulic system. In this paper, a discussion for challenges in model-based nonlinear con- trol, latest developments hydraulic servo systems are and brief perspectives of presented： Modelling uncer- tainty in hydraulic system is a major challenge, which includes parametric uncertainty and time-varying distur- bance; some specific requirements also arise ad hoc difficulties such as nonlinear friction during low velocity tracking, severe disturbance, periodic disturbance, etc.; to handle various challenges, nonlinear solutions including parameter adaptation, nonlinear robust control, state and disturbance observation, backstepping design and so on, are proposed and integrated, theoretical analysis and lots of applications reveal their powerful capability to solve pertinent problems; and at the end, some perspectives and associated research topics （measurement noise, constraints, inner valve dynamics, input nonlinearity, etc.） in nonlinear hydraulic servo control are briefly explored and discussed.
基金supported by the National Natural Science Foundation Project of CQ CSTC of China (2008BB2168)
文摘The error vector magnitude（EVM） is extensively applied as a metric for digital transmitter signal quality compliance in modern communication systems.This article is focused on the effects of local oscillator（LO） phase noise and nonlinear distortion of power amplifier on EVM.This article contributes to below aspects.First,the relationships between EVM and two effects,LO phase noise and nonlinear distortion of power amplifier,are derived and expressed.Second,to simplify the expression,the third-order intermodulation distortion（IMD3） is used to calculate the EVM.Then,an expression for the EVM is derived based on the digital transmitter model that considers local oscillator phase noise and nonlinear distortion of power amplifier.Finally,the math formula of bit error rate（BER） versus EVM is given which can be easier and more useful to predict BER,according to analysis of the relationship between EVM and signal to noise rate（SNR）,inspired by the works of Rishad,Md.Shahriar and AHM,2006.Simulations are carried out to display the performance of EVM based on these relationships.
